Chapter 7 - Section 7.2 - Assess Your Understanding - Explaining the Concepts - Page 380: 55

$P(Z \geq)$ should be considered as >0.9999 Note that we should not round to "1.0", since this could give the impression that the event is certain to occur (i.e. will always occur).

First we need to calculate the z score: $z = \frac{x - μ}{σ} = \frac{220 - 100}{15} = 7.33$ $P(X \geq 30) = P(z \geq 7.33) = 0.9999$ Hence $P(Z \geq)$ should be considered as >0.9999